| 摘要 |
PURPOSE:To make excess power consumption zero when no communication is attained by supplying a power to a driver circuit and a receiver circuit only when communication is applied. CONSTITUTION:A CPU 2, a communication controller 3 and a power control circuit 4 are connected to a power supply circuit 1. Further, the controller 3 is connected to the CPU 2 by buses 22, 32 and a data terminal ready ER signal output terminal 33 is connected to a driver circuit 5 and a control terminal 43 of the circuit 4. When an ER signal is outputted before the communication is attained, transistors (TRs) 401, 402 of the circuit 4 are turned on and power supply is given to the circuit 5 and the receiver circuit 6. At the end of communication, when the ER signal is turned off, the TRs 401, 402 are turned off and the power to the circuits 5, 6 is not supplied.
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